Semiconductor devices, e.g. for use in computer systems or the memory devices thereof are usually constructed in module form. A conventional memory module essentially has two main groups of components. Firstly active and passive electrical circuit components and secondly a printed circuit board. The printed circuit board serves as a carrier for the circuit devices, provides connection elements such as conductor tracks and brings about a connection toward the outside.
Active electrical circuit devices, such as e.g. memory chips, are individual, packaged chips. The following functions are realized within the package: connection between contact pads of the chips to form a type of rewiring (leadframe, interposer board). This can be effected by means of bonding processes or by means of small solder balls as an interconnect element. This rewiring serves as a contact element for the next architectural level—connection to the application printed circuit board. Passive circuit components such as e.g. resistors, capacitors, etc. essentially serve for the external connection of the active circuit devices.
Electrical circuit components are soldered onto a circuit board during module assembly. The use of conventionally packaged active circuit devices results in a comparatively low component density and the thickness of the modules lies in the range of about 2 to 3 mm.
FIG. 12 diagrammatically illustrates the population of a printed circuit board 29 with active and passive circuit devices 12, 13. Active circuit components 12, such as e.g. memory chips, are seated on an interposer substrate 30 provided with a connecting device 28, e.g. solder balls on soldering pads, for the purpose of electrical contact-connection to the printed circuit board 29. Passive circuit components 13, such as e.g. resistors, capacitors, etc., are likewise provided on the printed circuit board 29.
FIG. 13 shows a customary multichip module having active and passive circuit devices 12, 13 on a printed circuit board 29. The active circuit devices or chips 12 are mounted on interposer substrates 30 using flip-chip technology (and additionally underfilled=adhesively bonded owing to the thermomechanical stability). The packages comprising chips 12 and interposer substrate 30 are fixed e.g. by means of solder balls 28 on the module carrier 29. Passive circuit devices 13 are soldered onto the circuit board 29, which have a large number of electrical connections such as conductor tracks between individual chips 12 or chips 12 and passive circuit elements 13. Such a customary arrangement thus has a high total thickness of at least d1+d2+d3 in the case of only one-sided placement, which leads to a module thickness of more than 2 mm, and furthermore results in a low component density since primarily the interposer substrate and conductor tracks have a large area requirement.
Therefore, it is an object of the present invention to provide a semiconductor circuit module and a method for fabricating semiconductor circuit modules whereby thin multichip modules with a high component density can be provided.